Ondetti in Belgian Pat. No. 861,454 disclosed mercaptoacyl derivatives of 4- or 5-thiazolidinecarboxylic acids as well as mercaptoacyl derivatives of 6-member hetero rings such as morpholine and thiamorpholine. These compounds are disclosed as being useful antihypertension agents due to their angiotensin converting enzyme inhibition activity.
Mercaptoacyl derivatives of proline and pipecolic acid are disclosed as useful antihypertension agents due to their angiotensin converting enzyme inhibition activity in U.S. Pat. No. 4,105,776 of Ondetti et al.
Mercaptoacyl derivatives of proline and pipecolic acid wherein the acyl sidechain can be substituted by an alkyl or trifluoromethyl group and the ring can be substituted with one or more halogens are also useful as angiotensin converting enzyme inhibitors as note Ondetti et al, U.S. Pat. No. 4,154,935.
Mercaptoacyl derivatives of proline and pipecolic acid wherein the acyl sidechain can be substituted with a lower alkylthio or mercaptomethyl group are also disclosed as angiotensin converting enzyme inhibitors by Ondetti et al. in U.S. Pat. No. 4,116,962.